The invention concerns a measuring device for measuring the diameter of a rotationally symmetric body, for instance a roll, of the type having at least one straight-line arm supporting on its free end a stylus for scanning the peripheral surface of the roll, with the arm featuring at least two rails which are parallel to each other, and are components of a jointed parallelogram serving to set the stylus on the peripheral surface or lift it from it. Such a measuring device is known from the German patent disclosure 34 12 253.
Such measuring devices are needed specifically for measuring the diameter of rolls for paper machines, Such rolls need to be ground in regular intervals. In grinding, determining the diameter exactly is indispensable, requiring maximum accuracies that extend into the micron range.
Such measuring devices must meet numerous requirements. The first requirement, as mentioned, is accuracy. The limits therefore and additional requirements are listed hereafter:
1. measuring accuracy--coincidental share: 0.001 mm (fluctuation); systematic share: 0.01-0.1 mm;
2. minimal or no limitation of the operator moving space;
3. no hindrance in case of grinding wheel change, groove cutting device; adjustable from the operating station;
4. no dependency of the measuring accuracy on settings made by the operator.